API version 1API version 1.1
Updated on Fri, 2014-06-27 10:27
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Introduction
With Twitter Cards, you can attach rich photos, videos and media experience to Tweets that drive traffic to your website. Simply add a few lines of HTML to your webpage, and users who Tweet links to your content will have a "Card" added to the Tweet that’s visible to all of their followers. Continue Reading

With the use of rel="canonical" to address content duplication issues, I feel sorry for website owners who use a publishing system that doesn't make generating a canonical URL for a given resource dead simple. Over and above the obvious search implications for doing that right, it is leveraged now by lots of different social elements, not necessarily the rel="canonical" tag itself but the concept of a canonical URL for a given piece of content. As social signals continue to evolve now and into the future, getting on top of what is on the surface a simple thing is going to become increasingly important.

This definitely sounds promising. I presume step (c) will follow in due course...
"To participate in the program, you should (a) read the documentation below, (b) determine whether you wish to support Twitter cards, and then (c) [node:7940,title="apply to participate"]"